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Microbiology > Exam 2: Cell Structure Part 2 > Flashcards

Exam 2: Cell Structure Part 2 Flashcards

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Biology 101 flashcards
1
Q

Define and contrast the terms cytoplasm and cytosol.

A

The contents of the entire cell are termed cytoplasm while the liquid portion of the cytoplasm is the cytosol. Cytosol is gel-like and mostly water, contains dissolved and suspended substances (ions, carbohydrates, proteins, lipids).

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2
Q

Where is bacterial genetic material present and what region contains it?

A

Present in the cytosol and contained in the nucleoid region.

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3
Q

Is the chromosomal DNA of a bacterium localized in any way? Explain.

A

Yes, localized in the nucleoid region but not enclosed with a nuclear membrane.

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4
Q

Do all bacteria possess chromosomal DNA?

A

No, but most do.

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5
Q

How many chromosomes do most bacteria possess?

A

Most possess a single chromosome but there are exceptions.

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6
Q

Compare the organization of bacterial DNA to that of eukaryotic DNA, especially in terms of coding and non-coding DNA.

A

Majority of bacterial DNA is coding while most of eukaryotic DNA is noncoding.

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7
Q

Compare the structure of a plasmid to the structure of chromosomal DNA.

A

Plasmid DNA is small, circular, and double stranded while chromosomal DNA is larger and circular. Both double stranded.

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8
Q

Do all bacteria possess plasmid DNA?

A

Nonessential, so not always present.

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9
Q

How might bacteria benefit from possessing plasmids?

A

Often contains genes for extra traits like antibiotic resistance.

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10
Q

Does plasmid DNA contain genes? Are any such genes of particular interest?

A

yes they contain genes. The antibiotic genes are of particular interest to scientists.

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11
Q

Compare the reproductive habits of bacteria to those of humans. How are they similar and how do they differ?

A

Reproduction is one directional, one bacteria donates to the other and thers no net growth in total number. Bacteria are also able to share DNA with different species unlike humans.

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12
Q

Explain the relevance of plasmids to biotechnology.

A

useful for manipulating and transferring genes in the laboratory. Scientists regularly transfer genes between species for various reasons. Glowing tobacco which possesses genes from fireflies or bacteria producing human insulin.

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13
Q

What processes rely on the cytoskeleton?

A

Cell division, cell shape determination, movement

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14
Q

Describe the structure of a ribosome. How are bacterial ribosomes and eukaryotic ribosomes alike, and how are they different?

A

Two subunits, one large and one small. Each composed of RNA and proteins. At the center there is a catalytic ribozyme core made of RNA. Fundamentally similar in both bacteria and eukaryotes. Some structural and functional differences, eukaryotic ribosomes are also larger.

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15
Q

Roughly how many ribosomes are present in a bacterial cell?

A

7,000-25,000+ per cell

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16
Q

What is the key function of a ribosome?

A

Protein synthesis

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17
Q

Why are bacterial ribosomes common targets of antimicrobial compounds?

A

Because there are some structural and functional differences that can be specifically targeted by antibiotics.

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18
Q

Are all genes are highly conserved over evolutionary time? Explain.

A

No, for many organisms they have duplicate genes and non coding genes plenty of munitions can happen that are lethal.

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19
Q

Why are genes encoding rRNA highly conserved over evolutionary time? In what way is this useful?

A

The function of ribosomes is critical to life so mutations are frequently lethal meaning they don’t get transferred to future generations.

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20
Q

When your favorite food is on sale, have you ever stocked up on this product? Do bacteria do anything like this? Explain.

A

Inclusions “storage granules”: Reserve deposits of useful molecules. Forms of lipids, starch, nitrogen, phosphorus. Take in when nutrients are abundant and used when nutrients are scarce. Specific example, polysaccharide glycogen and polydroxybutante (PHD).

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21
Q

Storage granules superficially resemble membrane-bound organelles possessed by eukaryotes. How are they alike and how are they different?

A

Sometime suspended by a peptide “membrane” not a true membrane.

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22
Q

Do all bacteria possess gas vesicles? Explain.

A

No, present in some aquatic cyanobacteria where is most useful for getting them up to the surface for photosynthesis.

23
Q

What is an endospore? How is it different than “normal” bacterial cells? Do all bacteria possess endospores?

A

Dormant cells with low metabolic rates, different then “normal” bacteria because it is not actively replicating. Not all bacteria possess endospores but common in soil.

24
Q

Describe the structure of a gas vesicle. What is its key function? Why might this be beneficial to some bacteria?

A

Specialized inclusion, small, rigid, protein bound compartments. Provides buoyancy to the cell getting it to the surface where light is available for photosynthesis.

25
Q

Why do bacteria produce endospores?

A

To preserve themselves in times of adverse environmental conditions and or when nutrients are scarce. It allows them to go dormant until environmental conditions improve. It protects from adverse conditions like death desiccation, radiation, and lethal chemicals.

26
Q

List at least three diseases caused by endospore-forming bacteria.

A

Clostridium botulinum-botulism
Clostridium tetani- Tetanus
Clostridium perfringens- Gas gangrene
Bacillus anthrax- anthrax

27
Q

Describe the process of endospore formation.

A

DNA replicates and the cytoplasmic membrane creates a split between the replicated DNA and the original DNA. The replicated DNA is encased while the original DNAdisingrates. The layers surrounding the replicated DNA continue to be fortified until it is released form te original cell.

28
Q

What conditions can promote the germination of an endospore? Briefly describe this process.

A

Briefly heating and cooling back down. Endospore takes on water and swells, spore coat and cortex crack open, vegetative cell grows out.

29
Q

Compare membranes of archaea to those of bacteria or eukaryotes. How are they similar and how are they different?

A

Membrane lipids lack phosphate groups, branched hydrocarbons linked to glycerol by ether linkages. Ether linkage is stronger than ester linkages so able to live in extreme environments. Similar to eukaryotic and bacterial membranes in that its hydrophobic/hydrophilic layer.

30
Q

Compare cell walls of archaea to those of bacteria. How are they similar and how are they different?

A
  • Lack phosphate groups.
  • Ether instead of ester. Ether are stronger.
  • Some have single layer of lipids with two polar heads.
  • Composed of specialized proteins or polysaccharides no Peptidoglycan.
  • Variable structure.
31
Q

Why do you think the cell wall structures of archaea are more diverse than those of bacteria?

A

More diverse due to wide range of extreme environment they can be found, some poses proteins that coat the cell like chainmail.

32
Q

Compare Gram-staining of archaea to Gram-staining of bacteria. What types of archaea cell architecture result in purple staining, and what types of archaea cell architecture result in pink staining?

A

Not true gram neg/gram positive but different structure do stain different colors. Can be stained with gram stain “gram neg” stain pink possess an outer layer of protein instead of an outer lipid bilayer. “gram neg” stain purple possess a tick cell wall.

33
Q

Compare glycocalyces and fimbriae of archaea to those of bacteria.

A

Glycoalyces resemble those in bacteria, function in biofilm formation but not demonstrated association with disease, no ninja status. Many possess fimbriae works like bacteria ones do, sticky, rod-like, non-motile.

34
Q

What are hami? Describe the structure of a hamus. What is their key function?

A

Unique fimbria-like structure, composed of protein. Helical filament with “prickles” similar to barbed wire. Ends are frayed into three distinct arms like a fishhook. Function in attachment to surfaces.

35
Q

Compare flagella of archaea to bacterial flagella.

A
  • Sperficially look like bacterial flagella (basal body, hood, filament).
  • Not covered by filament.
  • Rotate clockwise and counterclockwise.
  • Significantly different proteins from bacteria but are similar archaea species to species.
  • Not hollow and are thinner than bacteria flagella.
  • Grow from the base not the tip.
  • Powered by ATP instead of proton flow.
  • Operates as a bundle.
36
Q

Are flagella of archaea homologous or analogous to those of bacteria? Explain.

A

Analogous structures, not homologous structures. Evolved independently of bacterial flagella so not homologous. Analogous development of structures that fit the same structure but developed differently.

37
Q

Compare the ribosomes of archaea to those of bacteria and those of eukaryotes.

A

Similar in size to bacteria, proteins are closure to those of eukaryotes. Chromosome are circular similar to bacteria.

38
Q

What types of organisms possess mitochondria? What is the function of mitochondria?

A

Found in most eukaryotic cells, site of the majority of cellular respiration (krebs cycle and electron transport chain).

39
Q

What types of organisms possess chloroplasts? What is the function of chloroplasts?

A

Found in plants and algae, site of photosynthesis.

40
Q

Mitochondria structure

A

surrounded by two membranes, outer membrane typically eukaryotic membrane, inner highly in folded and is involved in energy transformations

41
Q

Chloroplast structure

A

surrounded by two membrane, outer typical eukaryotic, inner is highly infolded and involved in electron transformation.

42
Q

Describe and compare the structures of mitochondria and chloroplasts. What is the basis of these similarities?

A

Both surrounded by two membranes, inner highly folded and involved in ATP synthesis, possess their own DNA, possess ribosomes similar size to bacteria, and reproduce independent of the cell.

43
Q

What is a chimera in Greek mythology? Why might it be difficult to appropriately classify this organism? Aside from being inherently fascinating, why is this mythical beast relevant to this unit of the class?

A

Hybrid creatures composed of a lion with the head of a goat coming out of its back, tail of a sneak head. Difficult to classify because it contains multiple characteristics from different species. Similar to cells that contain chloroplasts and mitochondria, they contain features of both eukaryotic cells and bacterial cells.

44
Q

Describe and compare the basic functions of mitochondria and chloroplasts. In what ways are they similar.

A

Both inner membranes are involved in ATP synthesis.

45
Q

List the features of mitochondria and chloroplasts indicate that they are the descendants of once free-living bacteria.

A
  • Electron transport pathways occurs in membrane folds
  • Highly infolded
  • Circular DNA
  • Contains ribosomes
  • Reproduce independent of the cell
46
Q

What portion of the mitochondrion corresponds to the bacterial cytoplasm? To the bacterial membrane?

A

Matrix corresponds to the bacterial cytoplasm. Inner membrane correspondence to bacteria membrane.

47
Q

What portion of the chloroplast corresponds to the bacterial cytoplasm? To the bacterial membrane?

A

Stromal corresponds to the bacterial cytoplasm. Inner membrane corresponds to bacteria membrane.

48
Q

Describe the endosymbiotic origin of mitochondria and chloroplasts.

A

Bacteria cells engulfed by early eukaryotic cells. Maintained rather than being digested. Started off parasitic but tired symbiotic. Both components bacterium and host benefited from the relationship and bacteria lost their ability to exist independently.

49
Q

Why do mitochondria and chloroplasts possess so few genes?

A

Most mitochondrial proteins are now encoded by genes in the cell’s nucleus. Circular molecule found in the “bacterial cytoplasm” . Not associated with histone proteins as in eukaryotic DNA. Consists almost exclusively of non-repetitive coding DNA.

50
Q

What group of bacteria are most closely related to mitochondria? How do we know this?

A

Alphaproteobacteria. The absolute closest living relative is rickettsia. Known through rRNA analysis.

51
Q

What group of bacteria are most closely related to chloroplasts? How do we know this?

A

Cyanobacteria, known through rRNA analysis.

52
Q

Describe the relationship between Rickettsia and its human host.

A

Causative agent of typhus, rocky mountain spotted fever. Obligate intracellular parasites, which must enter the host cell to complete their life cycle, suppresses fusion with the host lysosome.

53
Q

What features of Rickettsia are relevant to the process of endosymbiosis?

A

It had means of entering a eukaryotic cell and maintaining itself avoiding digestion.

54
Q

Which of the following terms does NOT accurately describe a typical bacterial chromosome?

Question options:
1. ALL of these terms accurately describe a typical bacterial chromosome
2. supercoiled
3. genetic material
4. double-stranded
5.linear
6. essential

A

Essential

Microbiology (30 decks)

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